Core C. Neuro-lmaging Core The Neuro-lmaging Core (Core C) will obtain structural and diffusion tensor Magnetic Resonance Imaging (MRI) scans of the subjects in this program project, and provide quantitative measures of specific anatomical structures for testing the hypotheses delineated in the scientific projects. Typically Developing children as well as in the clinical populations under study in this proposal (Specific Language Impairment, Focal Brain Lesions, High Functioning Autism, and Williams Syndrome) will be scanned shortly after enrolment in this study. MRI provides high-resolution images of the human brain with minimal risk, and thus is appropriate for children. From their differential tissue properties and relative anatomical locations, it is possible to delineate and quantify different subcortical structures and cortical areas. Similarly, white matter tracts can be localized from diffusion tensor MRI. Recently, reliable and validated tools have been developed to automatically and exhaustively label cortical and subcortical structures in adults. Labelling of white matter tracts is less validated but under rapid development. We propose in this Core to modify these tools so that they operate reliably in the pediatric population, specifically quantify anatomical entities relevant to the hypotheses advanced in the individual projects, and validate their performance in target and control populations. Our overall goal is to provide quantitative measures of human brain anatomy that can be correlated with the neuropsychological and psychophysiological measures, as well as the clinical status, of the pediatric populations included in this Program Project.